Impact tool



May 26, 1959- c. vEa. slEBER 2,888,246

IMPACT Toor.

2 Sheets-Sheet 1 Filed June 5, 1955 c. B. slEBr-:R 2,888,246

lMay 26, 1959 IMPACT TOOL 2 Sheets-Sheet 2 Filed June 5, 1955 UnitedStates Patent O IMPACT TOOL Charles B. Sieber, Villa Park, Ill.Application June 3, 1955, Serial No. 513,093 13 claims. (ci. zss-ss) Myinvention relates to a power-operated impact tool and has particularreference to a tool in which an impact is directed upon a working partof the mechanism and may be used for a multiplicity of purposes such asbreaking up concrete structures like concrete driveways, walls, walks,pavements, etc., such tools being commonly known in the trade asdemolition tools and, by the substitution of working parts, may beconverted into driving mechanisms for driving spikes, a sheet-drivingtool, or the like, depending upon the particular character and kind ofwork being performed.

Another object of my invention is the provision of an electricallyoperated impact tool shown embodied and described in a demolition toolprimarily adapted for breaking up concrete structures, regardless ofwhether it be in walls, roadways, sidewalks, or the like, and which maybe operated by various kinds of power applying means-the device shownbeing operated by electric power supplied through a motor mounted in'the tool, although hydraulically operated motors may be used as well asvarious other means by which power in the form of impact blows isdelivered to a working tool.

Another and further object of my invention is the pro-v vision of a toolin which a rotary impact member is provided which may be operated by anelectric motor and in such manner that a series of heavy blows Vcan bedirected against a tool for demolition work and which operates veryrapidly, so that the force exerted on the working end of the tool isvery considerable and at the same time a certain amount of vibration isimparted to the tool and to the structure being broken, whichas sists inbreaking up and cracking the structure, such as concrete, and the like.

Another and further object of my invention is the provision of a -toolwhich can be operated by an electric motor thus doing away with the useof air -compressors and the like in the operation of tools of this typeso that the tool may be operated by connecting vit to a suitable sourceof electric power which is often available close by without thenecessity of lusing an air compressor and motor power for operating theair compressor, which must be hauled onto the job, thereby providing anextra amount of labor, etc. in keeping the airy compressor in operationto supply the power to operate the demolition tool.

Another and further object of my invention is the provision of anelectrically operated demolition tool which takes the place of airoperated demolition tools now in common use and which is simple inconstruction, simple in operation and in which the force of the blowscan be greater than that of an air hammer of the same size and in whichthe tool itself is much more easily held in position by the operator andbecause the tool is not subject to as much vibration as are air hammers.

Another and further object of my invention is the provision of ademolition tool which is substantially selfcontained and which needsonly to be supplied with electric current in order to provide power forthe operationl ICC of the tool, without the necessity of providing extraIcompressor equipment such as is commonly employed at the present time.

These and other objects of my invention will be more fully and betterunderstood by reference to the accompanying drawings and in which- Fig.1 is a side elevational view bodying a demolition tool.

Fig. 2 is a front elevational view of the tool shown in Fig. 1.

Fig. 3 is a vertical sectional view of the working parts of the toolshown in Figs. y1 and 2 on line 3--3 of Fig. 4.

Fig. 4 is a vertical sectional view through the working parts of thetool on line 4--4 of Fig. 3.

Fig. 5 is a vertical sectional view of the working parts of the toolshowing the impact head in extended position on line 5--5 of Fig. 4. g

Fig. 6 is a vertical sectional View of the working parts showing theIimpact tool in retracted position .-takenfon line 6 6 of Fig. 4.

Fig. 7 is a vertical sectional view showing the impac head in extendedposition on line 7-7 of Fig. 4, and

Fig. 8 is a perspective view of the movable yoke and cam and the impacthead secured thereto.

Referring now specifically to the drawings and in whichlike referencecharacters refer to like parts throughout, a base plate 10 is shownhaving a flange 11 at one end thereof, with an integrally yformed cover12 being prof vided which has three closed sides and a closed top andbottom and which has its edges fitted over the side edgesof the plate 10and ange 11 and is secured to the plate 10 and ange 11 by means of bolts13, 13 which provides a complete housing for the main working parts ofthe tool. The cover has a top portion 14' and curved bottom 15, with acurved' rear side 16 and is shaped generally to conform to the contourof the mechanism enclosed in the housing at the rear side of the tool,so that the opera-y tor in grasping the handle 17 with both of his handsdoesy not have his view obstructed to the workpiece by the` housing. Thehandle 17y is secured'to the top 14 of the housing by means of a bracket18.

Spaced brackets 19 and 20 are-provided which are secured to the baseplate 10 alongeach of its sides by bolts 21, 21 extending through thebase portion 22, 22 of the brackets 19 and 20 and through the base plate10, upon which brackets 19 and 20 a rotatably driven axle 23 is mounted,the axle 23 having an enlarged central' portion 24, with the ends of theaxle 23 beingjournalled in the brackets 19 and 20 and held in positionby cap members 25v and 26 secured to the brackets 19 and 20`respectively by bolts 27, 27. A'belt wheel 28 is mountedy upon one endof the axle 23 having a driving belt 29 lextending thereover which leadsto a pulley 30 on the projecting end of a motor shaft 31 of a motor 32which is mounted on the inner face of the base plate 10 by means of abracket 33 secured to the base plate 10 by means of bolts 34, 34.Suitable electrical lead connections are provided (not shown) which leadthrough a switch (also not shown) mounted in the handle 17 andr to anysuitable source of electric power by means oft which' power the motor isoperated as desired.

A built up wheel designated as a whole as 35 isk provided which isrotatably mounted on the-axle 23` and which consists of circular-sideplates 36 ar'1d'37 having central circular openings therein, and havingyinwardly of my invention emextending trunnions 38 and 39 thereon whicharespaced:

axle 23. A cam 41 is provided which is mounted on the enlarged portion24 of the axle 23 and is secured to the axle 23 by means of a key 42 sothe cam 41 moves in fixed rotation with the axle 23. The cam 41 has ahigh cam lsurface 43 and a low cam surface 44 thereon, substantiallyopposite each other, and has a projection 45 thereon extending outwardfrom the cam 41 adjacent the high surface 43 at the rear surface thereofas the cam rotates, with a hook 46 thereon for purposes hereinafterdescribed.

The wheel 35 has a rim 47 thereon which is mounted between the outeredges of the circular side plates 36 and 37 and is secured to the saidside plates by means of a plurality of bolts 48, 4S which extend throughthe side plates 36 and 37 and through the rim 47. The rim 47 has achannel 49 therein which does not extend entirelyl around the plates 36and 37 but has a portion cut out to form an opening Si) therein, forpurposes hereinafter described. The channel 49 is arcuate or concave asshown. Yokes 51 and 52 are provided having extensions 53 and 54 thereonat one of their ends upon which an impact head 55 is mounted, the impacthead having slots 56 and 57 therein into which the extensions 53 and 54are fitted, With a pin 57 extending transversely through the impact head55 and the extensions 53 and 54, with a portion 5S of the head 55 beingpositioned between the yokes 51 and 52,'which acts as a spacer for theyokes 51 and 52 and also has a cam follower, and has a cam member 59which is fitted between the yokes 51 and 52 at their ends opposite theimpact head 55, which is secured between the yokes 51 and 52 by means ofrivets 60, 60 and which also acts as a spacer for the yokes 51 and 52.The ends 61 and 62 of the yokes 51 and 52 are arcuate in contour andconform to the curvature of the inner surface of the rim 49 forming apart of the wheel 35, while a portion of the ends 63 and 64 adjacent theimpact head 55 is also arcuate in contour, conforming lgenerally to thecurvature of the inside surface of the rim 47 of the wheel 35. The yokes51 and 52 have elliptical openings therein into which trunnions 3S and39 extend which form support bearings for the sliding movement of theyokes 51 and 52 which are less in length than the internal diameter ofthe wheel 35, and are arcuate in shape at each of their ends to conformto the curvature of the rim 49 forming a part of the wheel 35. Theimpact head 55 extends into the opening 50 in the wheel rim 47 and is ina close sliding position on the surfaces of the rim 47 adjacent theopennig 50 outward across the channel 49 in the rim 47 and between theplates 36 and 37 and moves to an impact position (Fig. and inward out ofimpact position (Fig. 6) depending upon the position of the yokes 51 and52 to which the head 55 is connected. The yokes 51 and 52 are spacedfrom each other so that the cam 41 may operate between them and for theprojection 45 to pass between the yokes for engagement with the camfollower 59 as the cam 41 rotates with the axle 23. The impact head 55is mounted at the lower corner of the yokes 51 and 52 in their endsopposite the cam follower 59, is generally rectangular in shape, and istted somewhat closely in the opening 50 and between the plates36 and 37with its side opposite the impact side substantially parallel to thecenter cross-sectional plane of the wheel 35 while its lower or impactside is parallel to a cross-sectional plane of a segment of the wheel ina line approximately one half the distance between the center of thewheel and the bottom of the channel 49 in the rim 47. The normalposition of the upper end of the transmission member 85 is parallel tothe segmented plane thus described, and because of the channel 49 andthe location of the transmission member with respect to the rim of thewheel, the entire surface area of the transmission member is within aplane tangent to the wheel at theouter edge of the wheel and the blow ofthe impact head 55 is delivered to the transmission member on alineperpendiularto therhorizontal plane of the wheel.

Spiral springs 65 and 66 are provided which have their outer ends 67 and68 respectively mounted in the plates 36 and 37 towards their outerperipheries and which are coiled about the axle 23 and have their innerends 69 and 70 respectively anchored into the side wall on each end ofthe enlarged central portion 24 of the axle 23. The springs 65 and 66are normally wound under some tension when the device is assembled andare so mounted that the rotation of the wheel 35 upon the axle 23 coilsthe spiral springs to a further degree, placing them under greatertension. The spiral springs 65 and 66 provide means by which the wheel35 receives the major portion of its rotative force from the axle 23during the operation of the device. Side plates 71 and 72 are mountedupon the axle 23 and secured thereto by threaded bolts 73, 73 so theplates 71 and 72 rotate in synchronism with the axle 23 but are spacedfrom the plates 36 and 37 so the springs 65 and 66 are held in a singleplane for efficient operation.

A shank member 74 is provided which is secured to' the base member 10 bymeans of bolts 75 and 76, with a collar 77 interposed therebetween andsprings 78, 78 mounted upon the bolts and 76, holding the shank securelyto the main frame. A spike tool 79 is mounted in the shank 74 in theusual manner of mounting these tools in air hammers and has a latch- 80which is normally fitted under a collar 81 on the spike 79 to hold thespike in position in the shank 74, this latch construction being of thesame type and kind now employed in the usual air hammers or demolitiontools. A guide tube 82 is provided at the upper end of the shank whichextends through an opening 83 in the flange portion 11, the tube 82having an arcuate shaped upper end 84 conforming generally to thecurvature of the outer periphery of the rim 47 and has a transmissionplug 85 which is circular in cross-section mounted therein and whichextends into the arcuate channel 49 in the rim 47 but out of contactwith the rim 47, so that as the wheel 35 is rotated, the impact head 55engages the upper end of the transmission member 35 which, in turn,transmits its force to the spike 79, thereby imparting a blow toconcrete or the like at the end of the spike 79. It will be understoodthat the working tool 79, which as shown is in the form of a spike, canbe removed and a spade, a digging tool, a cutting chisel, a tamper, orthe like, can be substituted therefor, as well as other tools such as aspike ydriver or sheeting driver now commonly used with air hammers fordemolition tools.

The assembly of the mechanism inside of the wheel 35 is accomplished byfirst placing the cam 41 in position between the yoke members 51 and 52and then placing this combination into position over the stub bearing onone of the plates 36 or 37, and after this assembly has been made theother plate forming the wheel and the rim 47 is placed into position andthis unit bolted together upon the axle 23, which combination canthereafter be inserted into position and mounted on the plate 10, withthe springs 65 and 66 being placed into position, as well as the plates71 and 72, and the unit mounted on the base plate 10 by placing the caps25 and 26 in position over the ends of the axle 23.

In the operation of the device, it will be understood, that the axle 23and the cam 41 mounted thereon are in constant rotation through powerbeing supplied thereto by the motor 32 through the belt 29 to the pulley28 on the shaft 23, while the rotation of the wheel 35, the yokes 51 and52 and the impact head 55 is intermittent and stops completely as eachblow is delivered by the impact head 55 to the transmission member 8S.Considering the parts in the positions shown in Fig. 5 with.

head 55 to the transmission member 85, the high side 43 of the cam 41 isapproaching the cam follower 59 (Fig, 6).V As this surface'43 of the cam41 engages the,y

follower 59 the yokes 51 and 52 are drawn radially inward of the wheel35 until the head 55 clears the transmission member 85 and the`projection 46 has engaged with the edge of the cam'follower 59, and thewheel 35, yokes 51 and 52 with the impact head 55 are free to rotate(Fig. The axle 23 has continued to rotate during the time the wheel 35has stopped rotation, thereby winding the springs 65 and 66 to a greaterextent than is in their normal condition thereby storing energy thereinto be later released. As the impact head 55 clears the transmissionmember 85, the wheel 35 resumes rotation, which rotative movement isinitiated by the radial thrust of the projection 45 against the trailingedge of the cam follower 59, and by the pull of the springs 65 and 66upon the wheel combined with the tension or energy stored in the springs65 and 66. The speed of rotation of the wheel 35 accelerates veryrapidly from its initial start of rotation until at the instant ofeachimpact of the head 55 the wheel 35 is travelling at least two and a halfto three times the speed of rotation of the axle 23 and cam 41 with anaverage speed of about twice that of the rotation of the axle Z3. Therapid accelerationand rotation of the Wheel in a very short period oftime is secured because the rotative force acting upon the wheel isapplied near the rim thereof instead of througha shaft upon which awheel is usually mounted because of the application of leverage to thewheel which is readily understood in the art. As shown in the drawings,the parts of the device just after the instant of irnpact of the head 55on the transmission member 85 is illustrated in Fig. 5 of the drawings,while in Fig. 6 the working parts of the tool are shown in theirrespective positions at the initial ,movement of rotation of the wheel35 after its rotation has been interrupted as an impact blow is beingdelivered by the impact head 55. As the speed of rotation of the wheel35 increases because of the pull of the springs 65 and 66, developed bythe rotation 0f the axle 23 plus the use of the stored energy in thesprings 65 and 66, the cam follower 59 moves on the surface of the cam41 towards the low side 44 thereof, centrifugal force causes the impacthead to move internally in the opening 50 in the wheel 35 towards theouter edge of the rim 49, while the impact head 55 is overtaking theprojection 45 on the cam 41, and as it does so, the surface 58 on theimpact head 55 engages the trailing side ofthe projection 45 therebybecoming a cam follower, and as the impact head passes over theprojection 45 the said head is forced outward into impact position inthe wheel rim 49, as the cam follower reaches the low side of the cam41, permitting this outward radial movement of the yokes 51 and 52. Thespeed of rotation of the wheel 35 continues to aocelerate as the impacthead 55 passes over the projection 45 until the wheel 35 is rotatingapproximately three times as fast as is the rotation of the axle 23,until the 1 working parts are in approximately the position shown inFig. 3 of the drawings, when a blow is delivered by the head 55 to thetransmission member 85, the rotation of the wheel 35 is interrupted, onecycle of operation has been completed and the parts are in position tocommence a new cycle of operation.

As a blow is delivered by the impact head 55 to the transmission member85, the entire reactive force developed as a result of the blow, istransferred from the head 55 to the wheel 35 and substantially absorbedby the springs 65 and 66 so there is no part of the tool subjected tosuch severe shock that breakage or extreme wear may develop with respectto any of the working parts. Likewise vibration of the tool is reducedto a minimum so a workman can easily hold a demolition tool of the typeshown in Figs. 1 and 7 of the drawings with less effort than is possiblewith a demolition tool operated by compressed air.

As a blow is delivered in the transmission member, the transmissionmember is driven downwardly slightly as the springs 78, 78 arecompressed, the reactive force is transferred to the wheel 35 the head55 is substantially freed of any friction at the sides and it is easilyand quickly drawn inward free of the transmission member without wear toany extent in the parts, and because of the particular construction ofmounting of the head as hereinabove explained, the impact blow isdelivered squarely upon the end of the transmission member.

The speed of rotation of the axle 23 can bevaried from 300 to 1000r.p.m., which means that every time the gear is rotated, a blow isdelivered to the working tool and which, in a rotation of 600 r.p.m.,delivers a succession of extremely powerful blows to the Working tool.Because of the fact that the opening in the rim 47 substantiallyconforms to the contour of the impact head 55, as the blow is deliveredon the transmis sion member theshock of this blow is transmitted to therim of the wheel, so that breakage of the impact head is very unlikely.Also, I have found that the tool is capable of delivering heavier blowsthan the ordinary demolition tool now in use through the use ofcompressed air and capable of doing extremely heavy work beyond thatpossible to be accomplished by the ordinary tools now in service.

While I have described more or less precisely the details ofconstruction, I do not wish to be understood as limiting myself thereto,as I contemplate changes in form, the proportion of parts and thesubstitution or' equivalents as circumstances may suggest or renderexpedient without departing from the spirit or scope of the invention.

What is claimed is:

1. An impact tool comprising in combination, a frame, a rotatable axlemounted thereon, a built up wheel corn-v prising a pair of side plateshaving inwardly turned trunnions at their centers to form an axialbearing for the said wheel and a rim secured to the said plates at theirouter edges having an opening therein, the said wheel being rotatablymounted on the said axle, a cam xed to the said axle and rotatabletherewith, a yoke having an elongated opening therein slidably mountedto move in an inwardly and outwardly direction on the hub of v the Wheelinternally thereof, a cam follower on the said yoke for co-operationwith the said cam on the said axle, an impact head on the said yokeextending into the opening in the rim of the wheel, and coiled spiralsprings on each side of the said wheel secured at their inner ends tothe said axle and having their outer ends secured to the wheel wherebythe rotative force of the axle near its outer periphery is communicatedto the said wheel.

2. An impact tool comprising in combination, a frame, a rotatable axlemounted thereon, a built up wheel comprising a pair of side plateshaving inwardly turned truunions at their centers to form an axiallymounting for the said wheel and a rim secured to the said plates attheir outer edges having an opening therein, the said wheel beingrotatably mounted on the said axle, a cam fixed to the said axle androtatable therewith, a yoke having an elongated opening therein slidablymounted on the hub of the wheel internally thereof to move in aninwardly and outwardly direction, a cam follower on the said yoke forco-operation with the said cam on the said axle, an impact head on thesaid yoke extending into the opening in the rim of the wheel, coiledspiral springs on each side of the said wheel secured at their innerends to the said axle and having their outer ends secured to f the wheelwhereby the rotative force of the axle near its outer periphery iscommunicated to the said wheel, and a pair of plates secured to the saidaxle and spaced from the sides of the wheel whereby the springs areretained in a single plane. l

3. An impact tool comprising in combination, a frame, a rotatable axlemounted thereon, a wheel having a hub portion and having an opening inthe rim thereof rotatably mounted on the said axle, a cam fixed upon theaxle and rotatable therewith the cam having high and low cam surfacesthereon substantially opposite each other on its outer periphery andhaving a projection thereon adjacent the high cam surface, a yoke havingan elongated opening therein slidably mounted within the said wheel onthe hub portion thereof adapted to move radially in an inward andoutward direction, a cam follower on the said yoke co-operating with thesaid cam to move the yoke radially of the wheel, an impact head mountedon the said yoke extending into the opening in the rim of the said wheeland movable inwardly and outwardly therein, spiral springs on each sideof the said wheel being their inner ends connected to the said axle andtheir outer ends to the said wheel near the outer periphery thereofwhereby the rotative force of the said axle is communicated to the saidwheel.

4. An impact tool comprising in combination, a frame, a rotatable axlemounted thereon, a wheel having side plates with inwardly projectingtrunnions therein to form hub portions and having an opening in the rimthereof rotatably mounted on the said axle, a cam iixed upon the axleand rotatable therewith, the cam having high and low cam surfacesthereon substantially opposite each other on its outer periphery andhaving a projection thereon adjacent the high cam surface, a yoke havingan elongated opening therein slidably mounted within the said wheel onthe trunnions forcing the hub portions thereof for inward and outwardradial movement in the said wheel, a cam follower on the `said yokeco-operating with the said cam to move the yoke radially of the wheel,an impact head mounted on the said yoke extending into the opening inthe rim of the said wheel and movable inwardly and outwardly therein,spiral springs on each side of the said wheel being their inner endsconnected to the said axle and their outer ends to the said wheel nearthe outer periphery thereof whereby the rotative force of the said axleis communicated to the said wheel.

5. An impact tool comprising in combination, a frame, a rotatable axlemounted thereon, a wheel having side plates with inwardly extendingtrunnions therein whereby hub portions are formed and having a rimthereon rotatably mounted on the said axle the said rim being arcuate incross section and having an opening therein, a cam fixed upon the axleand rotatable therewith, the cam having high and low cam surfacesthereon substantially opposite each other on its outer periphery andhaving a projection thereon adjacent the high camming surface, a yokehaving an elongated opening therein and slidably mounted within the saidwheel on the hub portions thereof for inward and outward radial movementwithin the wheel, a cam follower on the said yoke co-operating with thesaid cam to move the yoke radially of tle wheel, and impact head mountedon the said yoke at one corner thereof and extending into the opening onthe said wheel and movable inward and outward therein, spiral springs oneach side of the said wheel having their inner ends connected to thesaid axle and their outer ends to the said wheel near the outerperiphery thereof whereby the rotative force of the said axle iscommunicated to the said wheel, and plates on the said axle spaced fromthe sides of the said wheel whereby the springs are retained in a singleplane.

6. An impact tool comprising in combination, a frame, a rotatable axlemounted thereon, a wheel having side plates thereon with inwardlyextending central trunnions thereon forming hub portions on the wheeland having a rim thereon rotatably mounted on the said axle the said rimbeing arcuate in cross section and having an opening therethrough, a camfixed upon the axle and rotatable therewith, the cam having high and lowcam surfaces thereon substantially opposite each other on its outerperiphery and having a projection thereon adjacent the high cammingsurface, a yoke having an elongated opening therein and Aslidablymounted for inward and outward radial movement within the said wheel onthe hub portions thereof, a cam follower on the said yoke cooperatingwith the said cam, an impact head mounted on the said yoke extendinginto the opening in the rirn of the said wheel and movable therein in aninward and outward direction, spiral springs on each side of the saidwheel having their inner ends connected to the said axle and their outerends to the said wheel near the outer periphery thereof whereby therotative force of the said axle is communicated to the said wheelwhereby the said springs are retained in a single plane, the said impacthead being mounted at one corner of the said yoke and olset from thecentral plane of the wheel.

7. An impact tool comprising in combination, a frame, a rotatable axlemounted thereon, a wheel having side plates thereon with inwardlyprojecting trunnions forming hub portions on the wheel and having a rimthereon rotatably mounted on the said axle and said rim being arcuate incross section and having an opening therein, a cam fixed upon the axleand rotatable therewith, the cam having high and low cam surfacesthereon substantially opposite each other on its outer periphery andhaving a projection thereon adjacent the high camming surface, a yokehaving an elongated opening therein slidably mounted within the saidwheel on the hub portion thereof, and movable radially of the wheel bythe said cam in an inward and outward direction, a cam follower on thesaid yoke co-operating with the said cam and the said projection, animpact head mounted on the said yoke extending into the opening on thesaid wheel and movable therein in an inward and outward direction,spiral springs on each side of the said wheel being their inner endsconnected to the said axle and their outer ends to the said wheel nearthe outer periphery thereof whereby the rotative force of the said axleis communicated to the said wheel, and plates in the said axle adjacentto the side plates of the said wheel whereby the springs are retained ina single plane, the said projection engaging the side of the camfollower after an impact blow to initiate rotation of the said cam inone of its positions and the rear of the impact head in another one ot'its positions and the rear of the impact head in another one of itspositions at the time an impact blow is delivered by the said impacthead whereby inward movement of the impact head is prevented.

8. An impact member comprising in combination a frame, a rotatable axlemounted in the said frame, a wheel rotatably mounted on the said axlehaving a recess in the rim portion thereof, a spiral spring wound aroundthe said axle connected to the axle at one of its ends and to the wheelat its outer end whereby rotative force from the axle is communicated tothe said wheel, the rotative force being constant and the movement ofthe wheel being intermittent, the rotative force from the axle beingabsorbed by the said spring during the non-rotative periods of the wheeland released to the wheel upon its resuming rotation, a striking membermovably mounted upon the wheel, having an impact head thereon extendinginto and slidably mounted within the recess in the said wheel, andmovable outward into impact position by the rotation o-f the wheel, andmeans whereby the striking member and impact head are withdrawn fromimpact position after each impact blow by the striking member.

9. An impact tool comprising in combination a frame, a power driven axlemounted on the frame, a wheel on the said axle rotatably mountedthereon, the said wheel having a hub portion and having a rirn portionwith an opening in the said rim portion extending radially therethrough,a spiral spring wound around the said axle and connected at its innerend to the said axle and at its outer end to the wheel whereby rotativemovement of the axle is transmitted to the said wheel, a rotatablereciprocating striking member mounted within and supported by portionsof the said Wheel, the said member having an impact head on its outerend extending into the opening in the said rim whereby the said strikingmember is rotated by the said wheel and an impact blow is delivered bythe said head to a receiving plug, the said impact head being in slidingengagement with the wheel rim, the said striking member and the saidhead being forced into impact position by centrifugal force impartedthereto by the rotation of the wheel and a cam mounted in the said axleand rotatable therewith in engagement with the striking member, and camfollowers in the said striking member for engagement with the said camwhereby the striking member is moved out of impact position with animpact receiving plug.

10. An impact tool comprising in combination a frame, a power drivenaxle mounted on the frame, a wheel on the said axle rotatably mountedthereon, the said wheel having a hub portion and having a rim portionwith an opening in the said rim portion extending radially therethrough,a spiral spring wound around the said axle and connected at its innerend to the said axle and at its outer end to the wheel whereby rotativemovement of the axle is transmitted to the said wheel, a rotatablereciprocating striking member mounted within and supported by portionsof the said wheel, the said member having an impact head on its outerend extending into the opening in the said rim whereby the strikingmember is rotated by the said wheel and an impact blow is delivered bythe said head to an impact receiving plug, the said impact head being insliding engagement with the wheel rim, the said striking member and thesaid head being forced into impact position by centrifugal forceimparted thereto by the rotation of the wheel, a cam mounted upon androtatable with the said axle in engagement with the said strikingmember, cam followers on the said striking member for intermittentengagement with the cam whereby the striking member is moved into andout of impact relation with a striking plug.

1l. An impact tool comprising in combination a frame, a power drivenaxle mounted on the frame, a wheel on the said axle rotatably mountedthereon, the said wheel having a rim portion with an opening in the saidrim portion extending radially therethrough, a spiral spring woundaround the said axle and connected at its inner end to the said axle andat its outer end to the wheel whereby rotative movement of the axle istransmitted to the said wheel, an inward and outward movable membermounted Within and supported by portions of the said wheel, the saidmember having an impact head on its outer end extending into the openingin the said rim and in sliding engagement therewith, the said member andthe said head being forced into impact position by centrifugal forceimparted thereto by the rotation of the wheel, and means within the saidwheel whereby the said member and striking head are withdrawn fromimpact position after the striking head has delivered a blow to animpact receiving member.

12. An impact tool comprising in combination a frame, a power drivenaxle mounted on the frame, a wheel on the said axle rotatably mountedthereon, the said wheel having a rim portion with an opening in the saidrim portion extending radially therethrough, a spiral spring woundaround the said axle and connected at its inner end to the said -axleand at its outer end to the wheel whereby rotative movement of the axleis transmitted to the said wheel, a striking yoke within the wheelhaving an impact head at one end thereof extending into the opening inthe said rim and slidably mounted therein, the said striking yoke beingslidably mounted on the hub of the wheel and having a reciprocalmovement within the said wheel into and out of impact position, the saidyoke being moved into impact position by centrifugal force impartedthereto by the rotation of the wheel, and means within the wheel wherebythe striking yoke is withdrawn from impact position after an impact blowhas been delivered by the impact head.

13. An impact tool comprising in combination a frame, a power drivenaxle mounted on the frame, a wheel on the said axle rotatably mountedthereon, the said wheel having a hub portion and having la rim portionwith an opening in the said rim portion extending radially therethrough,a spiral spring wound around the said axle and connected at its innerend to the said axle and 'at its outer end to the wheel whereby rotativemovement of the axle is transmitted to the said wheel, a striking yokecomprising a pair of members, combined cam followers and spacers mountedbetween the yoke members at each of the ends of said yoke, Ian impacthead on the outer end of the said striking yoke extending into theopening in the said rim and in sliding engagement with the wheel rim,the yoke members being supported by the hub portion of the wheel, and acam xed on the said axle and rotatable therewith for engagement with thecam followers whereby the yoke and impact head are moved into and out ofengagement with an impact receiving plug at predetermined times.

References Cited in the le of this patent UNITED STATES PATENTS 683,533Waite Oct. 1, 1901 731,569 Heimrich June 23, 1903 917,731 Jackson Apr.6, 1909 1,492,535 Rasch Apr. 29, 1924 FOREIGN PATENTS 651,339 FranceOct. 9, 1928 707,677 Great Britain Apr. 21, 1954 707,678 Great BritainApr. 21, 1954

